Adaptive Signal Analysis Based on Radial Parabola Kernel

Abstract:

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Because of the deficiency of fixed kernel in bilinear time-frequency distribution (TFD),
i.e. for each mapping, the resulting time-frequency representation is satisfactory only for a limited
class of signals, a new adaptive kernel function named the radial parabola kernel (RPK), is
proposed. The RPK can adopt the optimizing method to filter cross-terms adaptively according to
the signal distribution, obtain good time-frequency resolution, and offer improved TFD for a large
class of signals. Compared with traditional fixed -kernel functions, such as Wigner-Ville
distribution, Choi-Willams distribution and Cone-kernel distribution, the superiority of the RPK
function is obvious. At last, the RPK function is applied to the analysis of vibration signals of
bearing, and the result proves the RPK function an effective method in analyzing signals.

Abstract: The traditional loading-strength interference model is used to calculate the reliability of components and system when random loading act once. In fact, components always work under repeated random loading, so it is important to derive a reliability model considering the frequency of loading. The two-dimensional distribution of random loading is proposed in this paper. In engineering practice, only a few samples of time-loading process can be obtained because of all kinds of limitation, so the reliability model based on transverse distribution of random loading. In addition, when it is difficult to know the exact distribution of random loading and strength, a discrete reliablity model is developed through the method of universal generating function. Finally, the reliability of system is analyzed considering common cause failure.

Abstract: In this paper, strength evaluations and reliability analysis are conducted for different types of PSSS(Periodically Symmetric Struts Supports) based on the FEA(Finite Element Analysis). The numerical models are established at first, and the PMA(Prestressed Modal Analysis) is conducted. The nodal stress value of all of the gauss points in elements are extracted out and the stress distributions are evaluated for each type of PSSS. Then using nonlinear least squares method, curve fitting is carried out, and the stress probability distribution function is obtained. The results show that although using different number of struts, the stress distribution function obeys the exponential distribution. By using nonlinear least squares method again for the distribution parameters a and b of different exponential functions, the relationship between number of struts and distribution function is obtained, and the mathematical models of the stress probability distribution functions for different supports are established. Finally, the new stress distribution model is introduced by considering the DSSI(Damaged Stress-Strength Interference), and the reliability evaluation for different types of periodically symmetric struts supports is carried out.

Abstract: Reliability of equipment has long been considered as an important quality characteristic. Traditional methods of equipment reliability assessment are based on lifetime data. With equipment being much more reliable and the growing need for developing new equipments within shorter period and at lower cost, we can hardly get enough lifetime data in many cases. Performance degradation data can also be used for reliability assessment. This paper is mainly researched on reliability of a certain diesel engine. Through analyzing the failure mode and failure mechanism, performance degradation parameters of the diesel engine is selected as compression pressure in a cylinder while driven by an electrical motor. Based on a long time accumulation on performance degradation data, two methods of degradation path fitting and degradation value distribution are tried in this paper to evaluate reliability of the diesel engine. Besides, the regulation of the reliability variation is given by the results of the assessment.

Abstract: In this paper the distribution of shear stress along the anchoring section of prestressed bolt was presented. The distribution of shear stress along the anchoring section of prestressed bolt was analyzed with the plane elastic theory. The analytical solution of shear stress along the anchoring section was deduced. Several cases of shear stresses were analyzed with the analytical solution. The results show that shear stress of prestressed bolt are not uniform distribution along the anchoring section; it is has no relations with the prestress value where the shear stress peak value is; the shear stress is at a certain range along the anchoring section; the shear stress peak value increases with the increase of prestress value;the larger the diameter of the anchoring section is, the less of shear stress peak value is.